This application is based on and claims priority to Japanese Patent Application No. 2000-111561, filed Apr. 13, 2000, the entire contents of which is hereby expressly incorporated by reference.
1. Field of the Invention
The present invention generally relates to the fuel system for internal combustion engines. In particular, the present invention relates to arrangement and structure of a fuel injection system for use with a multi-bank engine (e.g., a V-type engine).
2. Description of the Related Art
Outboard motors often are mounted on transoms of power boats and similar watercraft to power such crafts. In this position, a powerhead of the outboard motor usually extends above the transom. The powerhead desirably is as compact as possible in order to minimize drag on the watercraft and to lessen any obstruction it may cause to the views of the boat""s occupants who are looking backwards. The powerhead thus affords only limited space for the engine and the associated components. One such component is the fuel system.
In order to improve the performance of engines employed in outboard motors, it has been proposed to utilize direct cylinder fuel injection in outboard motor fuel systems. Such direct injection systems, especially 2-cycle engines, generally require higher pressure pumps than utilized with normal manifold-type fuel injection systems. This is because in a two-cycle engine the fuel must be injected at a pressure higher than that in the combustion chamber when the ports are closed. This pressure is considerably higher than the pressure in the induction system, which is where conventional manifold injectors inject and which is usually at or below atmospheric pressure.
On the other hand, it is generally undesirable to store and/or maintain fuel at very high pressures over long lengths of time and distance. It therefore is preferred to provide and drive high-pressure pumps in the powerhead to elevate the fuel to the pressure required at the injectors. Because of the high pressures required, some fuel systems use an engine-driven high-pressure pump rather than an electrically-operated fuel pump. Also, some systems use a series of pumps to elevate the fuel pressure to achieve the required pressures. Employing multiple fuel pumps unfortunately can greatly increase the number of parts in the fuel system, complicating assembly and maintenance, and also leaving little space for the other engine components.
An aspect of the present invention involves an outboard motor comprising a powerhead including an internal combustion engine. The engine has at least one variable-volume combustion chamber formed by at least a pair of members. One member is movable relative to the other member. A crankshaft is coupled to the one member and is journaled for rotation within the engine. Ann intake system is configured to provide air to the combustion chamber. A fuel system includes a fuel supply system and at least one fuel injector that is connected to the fuel supply system and is arranged to provide fuel to the at least one combustion chamber. The fuel supply system comprises a fuel circuit including a plurality of conduits and having a multi-branched portion. A plurality of high pressure fuel pumps are disposed in separate branches of the multi-branched portion. A vapor separator is disposed between a fuel filter and the multi-branched portion. At least one of the branches of the multi-branched section loops back to form a looped branch in the fuel circuit to communicate with the vapor separator.
Another aspect of the present invention involves an internal combustion engine comprising a pair of cylinder banks. Each bank has at least one cylinder, and a fuel injector is mounted on each of the banks and is arranged to provide fuel to the respective cylinder. A fuel system comprises a fuel circuit, which extends between a fuel tank and the fuel injectors. A plurality of high pressure fuel pumps are disposed within the fuel circuit. Each of the pumps is connected to a respective fuel injector to supply high pressure fuel to the injector. The pumps are arranged within the fuel circuit such that the inlet of one pump does not communicate with the outlet of another.
In accordance with another aspect of the present invention, an outboard motor is provided comprising an internal combustion engine. The engine has at least one variable-volume combustion chamber formed by at least a pair of members. One member is movable relative to the other member. A crankshaft is coupled to the one member and is journaled for rotation within the engine. An intake system is configured to provide air to the combustion chamber. A fuel system includes a fuel supply system and at least one fuel injector that is connected to the fuel supply system and is arranged to provide fuel to the at least one combustion chamber. The supply system comprises at least two high pressure fuel pumps and a pump drive unit arranged to drive the two high pressure pumps.
An additional aspect of the present invention involves an outboard motor comprising an internal combustion engine. The engine has at least one variable-volume combustion chamber formed by at least a pair of members. One member is movable relative to the other member. A crankshaft is coupled to the one member and is journaled for rotation within the engine. An intake system is configured to a provide air to the combustion chamber. A fuel system includes a fuel supply system and at least one fuel injector that is connected to the fuel supply system and is arranged to provide fuel to the at least one combustion chamber. The fuel supply system comprises a fuel circuit including a plurality of conduits and having a multi-branched portion. The fuel supply system also includes a plurality of high pressure fuel pumps. The pumps are disposed in separate branches of the multi-branched portion.
Further aspects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments.